Turbine nozzle



F 1944- R. P. KROON ET A1. 48

TURBINE NOZZLE Filed March 8, 1941.

Rsmcu'r P. Km "R D Guam. ER.

INVENTORS ON as F?- MEY Dv. (7%,M

WITNESSES: -53

Patented Feb. 8, 1944 TURBINE NOZZLE Reinout P. Kroon, Swarthmore, andCharles A.

Meyer, Drexel Hill, Pa., assignors to Westinghouse Electric &Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsyl-Vania Application March 8, 1941, Serial No. 382,321

3 Claims. (Cl. 253-48) This invention relates to elastic-fluid turbineimpulse stages and it has for an object to reduce shock of the movingblades.

We have found that, where a large proportion of the total turbinepressure drop occurs across the first partial peripheral admissionimpulse stage, the shock experienced by the moving blades leaving thezone of action of the last nozzle passage of a nozzle group isparticularly severe, that is, the very large steam force acting acrossthe blades is at that time suddenly removed. We have greatly reducedshock under these circumstances by restricting admission of steam to thelast nozzle passage of the group, and it is a more particular object ofthe present invention to provide apparatus of this character and servingthis purpose.

A further object of the invention is to provide a nozzle constructionfor an elastic-fluid turbine wherein the nozzles are arranged asadjacent primary and secondary groups with the final and initial nozzlepassages thereof common to both groups.

These and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawing, forming a part of this application, inwhich:

Fig. 1 is a fragmentary developed sectional view of an impulse turbinestage having the improvement applied thereto;

Figs. 2, 3, 4 and 5 are views similar to Fig. 1 but showing alternativeforms of the improvement;

Fig. 6 is a fragmentary side elevational View of 1 the nozzles shown inFig. '7

Fig. 7 is a view similar to Fig. 1 and taken along the line VII-VII ofFig. 6; and

Fig. 8 is a transverse sectional view of the turbine stage shown in Fig.'7 and taken along the line VIIIVIII of Fig. 6.

In Fig. 1 there is shown an impulse stage, at it, embodying stationaryvanes or blades I I and moving vanes I2, the stationary vanes providingnozzle passages l3 and I3a for supplying elastic fluid to the bladepassages I2a.

As shown, the nozzle passages I3 are arranged in adjacent primary andsecondary groups I4 and I5 supplied from adjacent nozzle chambers I6 andI1 and separated by an intermediate nozzle passage I3a.

With the conventional impulse stage, where the pressure drop across themoving blades is a large percentage of the initial pressure, the shockon the moving blades leaving a nozzle group or zone is very pronounced.This shock may be reduced by limiting the supply of elastic fluid to thefinal nozzle passage of the group. Instead of the noz zle passages Itbeing arranged as primary and secondary groups, at I4 and I5, andserving alone to supply elastic fluid separately from the nozzlechambers I6 and I! to the blade passages,

there is provided a nozzle passage I3a disposed intermediately of thegroups and which communicates with adjacent ends of the chambers I 6 andI! to serve as a common nozzle passage for the latter. In other words,the'pa'ssage i3c functions as the final nozzle passage with the primarynozzle group, at I l, and as the initial nozzle passage with thesecondary nozzle group, at I5. Therefore, with steam supplied only tothe primary nozzle chamber IS, flow therefrom through the nozzle passageI3a will be substantially less than through each of the nozzle passagesI3 of the group at I4, and, in consequence, the shock on moving bladesleaving the group will be reduced as compared to the usual arrangementwhere full flow occurs through the final nozzle passage. While it isinherent that flow through the nozzle passage I3a shall .be less thanthrough the passages I3 when steam is supplied only to the primarynozzle chamber I5, nevertheless, as steam is admitted to the secondarynozzle chamber I1 and such admission is progressively increased, thenozzle passage I3a becomes more and more effective until, with fullsteam admission to the secondary nozzle chamber, such passage is justabout as effective as any of the nozzle passages I3.

In Fig. 1, the nozzle box or chamber partition I8 has its rear edgejoined to the inlet edge 22'] of the vane I I separating the nozzle I3afrom the adjacent nozzle passages I3 of the primary group. at I4, andelastic fluid is supplied to the nozzle passage Ha through a port 22formed in the par tition. As the partition I8 provides for substantialcommunication of the secondary nozzle chamber with the nozzle passageI3a, it will be apparent that such nozzle passage is common both to theprimary and to the secondary nozzle chambers, it functioning as thefinal nozzle passage with the primary group, at It, and as the initialnozzle passage with the secondary group, at I5.

Assuming the admission of steam only to the primary nozzle chamber I6,it will be apparent that the restricted communication thereof with thenozzle passage I3a assures of such limitation of flow through the latterthat moving blades leaving the zone of action thereof will have shockondary nozzle chamber I! and such admission is progressively increased,the common nozzle pas sage I3a for the adjacent primary and secondarynozzle groups becomes more and more effective until, with full steamadmission to the secondary nozzle chamber I I, the nozzle passage I3a isjust about as eifective as any of the nozzle passages I3. I

In Fig. 2, the structure is somewhat like that already described, thepartition I811 is provided with an opening 22a inclined inwardly in thegeneral direction of the initial passage Ho and formed in the junctionregion between the partition Illa and the inlet edge 20 of the nozzlevane I I.

In Fig. 3, the partition I81) is formed separately from the vanes II, itconstituting a part of the nozzle box chambers or structures I6 and I1and defining passages 23 and 25 for supplying elastic fluid from thenozzle chambers I6 and I! to the nozzle passage I3a.

In Fig. 4, the partition I80 has Wall portions 25 arranged adjacent tothe nozzle vanes II, the partition structure having openings 26 and 27for supplying elastic fluid from the primary and secondary nozzle groupsto the common nozzle passage I ta for the adjacent nozzle groups I 4 andI5.

In Figs. 6, 7, and 8, there is shown a further modified form ofpartition structure for the primary and secondary nozzle chambers. Inthese views, the primary nozzle chamber It has an outer portion 28 whichoverlaps radially an inner portion 29 of the secondary nozzle chamberII, the partition structure comprising inner and outer wall elements 3|and 32 arranged adjacent to inlet edges of the vanes I I and beingjoined by a circumferential element 33. The nozzle passage I3a has acircumferentially-extending partition 34 aligned with the partition 33and dividing the nozzle passage I3b into inner and outer radialportions.

In Fig. 5, the partition I8d cooperates with a nozzle vane II, as inFigs. 1 and 2, but, instead of providing an opening in the partition forsupplying steam from the primary chamber to the nozzle passage I3a, thevane has an opening 36 for supplying steam to such nozzle passage.

While the invention has been shown in several forms, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various other changes and modifications without departingfrom the spirit thereof, and it is desired, therefore, that only suchlimitations shall be placed thereupon as are specifically set forth inthe appended claims.

What is claimed is:

5 1. In an elastic-fluid turbine, means providingcircumferentially-adjacent primary and secondary nozzle chambersseparated by a partition structure, a row of moving blades, and aplurality of vanes providing nozzle passages for discharg- 10 ingelastic fluid from the primary and secondary chambers to the blades,said partition structure cooperating with the vanes to divide the nozzlepassages into primary and secondary groups separated by an intermediatenozzle passage with the primary and secondary groups supplied withelastic fluid only from the primary and secondary nozzle chambers,respectively, and to provide entrance openings from both the primary andsecondary nozzle chambers to the intermediate nozzle passage.

2. In an elastic-fluid turbine, means providingcircumferentially-adjacent primary and secondary nozzle chambersseparated by a partition structure, a row of moving blades, and aplurality of vanes providing nozzle passages for discharging elasticfluid from the primary and secondary chambers to the blades, saidpartition structure cooperating with the vanes to divide the nozzlepassages into primary and secondary groups separated by an intermediatenozzle passage with the primary and secondary groups supplied withelastic fluid only from the primary and secondary nozzle chambers,respectively, and to divide the entrance to the intermediate nozzlepassage into portions open to the primary and secondary nozzle chambers.

3. In an elastic-fluid turbine, means providingcircumferentially-adjacent primary and secondary nozzle chambersseparated by a partition structure, a row of moving blades, andplurality of vanes providing nozzle passages for discharging elasticfluid from the primary and secondary chambers to the blades, saidpartition structure cooperating with the vanes to divide the nozzlepassages into primary and secondary groups separated by an intermediatenozzle passage with the primary and secondary groups suppli d withelastic fluid only from the primary and secondary nozzle chambers,respectively, and with the entrance to the intermediate nozzle passageopen to the secondary nozzle chamber and being joined to the inlet edgeof the vane separating the intermediate nozzle passage from the adjacentnozzle passage of the primary group and said partition structure havingan opening formed therein at the entrance of said intermediate nozzlepassage for supplying elastic fluid from the primary nozzle chamberdirectly to such nozzle passage.

REINOUT P. KROON. CHARLES A. MEYER.

